Try do an extra bit of walking every day. Going to the shops? Walk. Take the long route for something, just generally be more active. I got a Fitbit ages ago and it was surprisingly motivating when it came to step count. If It was evening and I was a bit short of 10k steps I'd just go for a quick walk to the shops.

Eat less food and ones that are less calorie dense, drink more water. Water makes you feel full and is healthy so try get an extra glass in. Don't wait until you are hungry, but randomly drink some water and it can extend the time before you are. Cut out sugar and sugary drinks in general. Don't cold turkey, but when I stepped down it was Sugar > Sugar Free > No added Sugar then finally just water.

Probably a bit extreme but if you are looking for a new job get one that's physically demanding. Since I switched work I lost weight, lost too much and actually struggled to gain it back.